The continuing effort to increase data storage capacity in magnetic disk drives is concerned largely with increasing the density of data that can be stored on the available recording surface area. Such assemblies typically include an elongated shaft or spindle, a hub fixed to the shaft and supporting the disks, and bearings and bushings at opposed ends of the shaft, to support the shaft, hub and disks for rotation relative to the disk drive housing. Also mounted movably with respect to the housing is an actuator, either of the rotary or linear type, for selectively positioning data transducing heads relative to the disks.
The design and manufacture of such drives involves disparate and often competing needs. The preferred high data storage densities require precision alignment of the disk pack and actuator, stability during rotation of the spindle assembly and resistance to thermal effects due to differing thermal expansion coefficients of materials employed in the drive. The housing must be strong, lightweight, resistant to vibration and provide an effective seal to prevent contamination of the housing interior, particularly in the region of the disks. At the same time, cost considerations stimulate efforts to reduce the number of parts and steps involved in assembling disk drives.
It is essential that the magnetic disc upon which information is to be stored is kept clean to avoid interference with the read/write heads which must operate in very close proximity to the surface of the disc. Toward this end, air is ordinarily circulated inside the compartment containing the rotating magnetic disc. Air may be passed through a filter to remove small particles from the gas within the compartment. Filtration of the gas surrounding the disc helps to maintain the clean atmosphere required for reliable operation of a magnetic disc.
However, materials will occasionally outgas from the components of the disk drive. If the outgassed materials are permitted to migrate and deposit onto a surface of the magnetic disc, interference with the reliable operation of the information storage and retrieval system is likely to result.
In order to inhibit the outgassing and aerosoling of grease from the central rotary bearings, shielded bearings (e.g. bearings having non-contacting rubber or metal shields) are ordinarily employed, but even these components are capable of outgassing a sufficient quantity of contaminants to interfere with operation of the information storage and retrieval system. One method of reducing aerosol contaminants is the use of structural means such as traps, seals, and filters.
Another alternative to using seals and filters is to degas component parts of the assembly. For example, Tanaka, et al., U.S. Pat. No. 4,619,798 Dec. 24, 1984 discloses a method of fabricating high purity SiC parts using a heating furnace includes a vacuum baking step at high temperature (800.degree. C. to 1300.degree. C.) for degassing the fabricated tube.
Kehlin, U.S. Pat. No. 3,953,663 also discloses a process step in the fabrication of dual sided printed circuit boards. Prior to soldering, the contaminants within the via holes are driven out by a vacuum bake step.
Further, each of U.S. Pat. Nos. 3,708,876 and 3,755,890 disclose a process step in the fabrication of dual sided printed circuit boards. Prior to soldering, the contaminants within the via holes are also driven out by a vacuum bake step.
However, even with the use of vacuum baking processes, problems exist. Baking processes can have deleterious affects on component parts. Also baking by simply heating may be only marginally effective depending upon the conditions of processing. Further, prior art processes have tended to generally focus on removal of constituents having a higher vapor pressure such as lubricants, greases, and fluids.
As a result, a need exists for a process which reduces gaseous contaminants present as part of disk drive components which may contaminate the disk drive environment.